1. Field of the Invention
The present invention relates to an ink jet printer device that prints printed matter without smearing while preventing an ejection failure caused by drying or thickening of an ink by humidifying an ejection portion during printing and a humidification method of an ejection potion.
2. Description of Related Art
As a device that ejects ink droplets, there is an ink jet type printer device (hereinafter, referred to simply as the ink jet printer device) configured to print an image and characters by making ink droplets be ejected onto a recording sheet as a recording medium from the head cartridge. The ink jet printer device has advantages that the running costs are low and it is easy to reduce the size of the device and to color a print image. In the ink jet printer device, inks of a plurality of colors (for example, yellow, magenta, cyan, black, and so forth) filled in the corresponding ink cartridges are supplied to the ink liquid chambers of the head cartridge.
The ink supplied to the ink liquid chamber of the head cartridge from the corresponding ink cartridge is pressed by a pressure generated by a pressure generation element, such as a heat resistor, provided inside the ink liquid chamber. The ink within the ink liquid chamber is consequently ejected from a fine nozzle provided to the head cartridge. In the following, a case where the heat resistor is used will be described concretely. The ink within the ink liquid chamber is heated by the heat resistor provided inside the ink liquid chamber to generate an air bubble on the heat resistor and an ink droplet is ejected from the nozzle by a pressure generated by this air bubble. The ink droplet thus ejected is allowed to land on a recording sheet as a recording medium to print an image and characters thereon.
The ink jet printer device configured as above possibly fails to eject an ink droplet during the printing because the ink dries or thickens at the ejection portion. To eliminate such an inconvenience, it is general to prevent drying of the ink by placing a cap on the ejection surface when not in use for printing or to remove the dried or thickened ink by ejecting tens to hundreds of ink droplets onto a non-print region immediately before the printing.
By removing the dried or thickened ink by the processing as above, the ink jet printer device becomes able to eject ink droplets from all the ejection portions when the printing starts. However, even when the ink jet printer device is in such a state when the printing starts, the ink gradually dries or thickens during the printing at an ejection portion that is seldom used during the printing.
Accordingly, when the ink jet printer device makes ink droplets be ejected nearly at the end of the printing from an ejection portion that has been seldom used during the printing, an ejection failure may possibly occur because the ink has dried or thickened.
Also, in order to avoid this problem, a type of a serial head ink jet printer device is provided with a portion that ejects ink droplets onto non-print regions on the both sides of a recording sheet when the head comes to the non-print regions. With this configuration, the serial head ink jet printer device prevents drying and thickening at a seldom used ejection portion.
On the contrary, it is difficult for a line head ink jet printer device to eject ink droplets onto the non-print regions in the middle of printing, which makes it difficult to print printed matter having a long print length.
An idea to humidify the ejection portion so as to prevent drying or thickening of an ink has been proposed in JP-A-2006-281539 before the present invention. This cited reference proposes a method of preventing drying and thickening at the ejection portion by wetting the ejection surface by pushing out the ink from the ejection portion while humidifying the vicinity of the ejection portion using a humidifier.
According to this humidification method, it is possible to humidify the ejection portion when not in use for printing but it is quite difficult to humidify the ejection portion during the printing.
Also, JP-A-64-71756 proposes a method of preventing drying and thickening at the ejection portion by impregnating a recording medium with moisture using a humidifier roller and heating the recording medium using a heating portion for letting the moisture evaporate from the recording medium. According to this method, it is possible to humidify the ejection portion during the printing. However, it is difficult to control an amount of humidification and smearing may possibly occur depending on the content of the printing.